The Effects of Simulated Breathholding Dives in the Dry and Wet Chambers on Blood Shifts into the Thorax.
NAVAL SUBMARINE MEDICAL RESEARCH LAB GROTON CONN
Pagination or Media Count:
Heart rate, blood pressure and transthoracic resistance changes were measured in 5 trained divers during simulated breathhold dives to 25, 50 and 90 feet in a wer and a dry chamber. During the wet dives heart rate fell significantly below control values and the transthoracic resistance changes provided evidence for blood shifts into the thorax. Reverse blood shifts out of the thorax developed at the end of breathholding on return to the normal atmospheric pressure. The dry dive on the other hand did not show any systematic changes in transthoracic resistance and the heart rate did not decrease significantly below control levels. The results of these studies clearly indicate that the hydrostatic effect of immersion on legs and abdomen forces the blood into the thorax. Blood shifts amounted to about 500 ml during breathholding when immersed on the surface and were in excess of one liter during breathhold dives to 25, 50 and 90 feet. Modified author abstract
- Stress Physiology